Like why is it not included in solar system i don’t get it
In: 20
Changes distance from sun significantly, Doesn’t revolve in the same ecliptic plane as planets, Smol.
For thousands of years, the word planet did not have a great definition. Planet basically meant star that moved around the sky in a weird way.
We finally decided that we needed a scientific definition of the word planet. When the people who decide these things made their definition, we learned that unfortunately Pluto did not fit that definition anymore, and while still being part of the solar system, it was not technically a planet.
If you want to dig into it more and really get the details, Mike Brown wrote a book about it. He discovered many of the Kuiper objects that “competed” with Pluto. The book is titled “How I Killed Pluto and Why It Had It Coming.” The “grandfathering” in of Pluto was actually discussed as part of the new definition of “planet.”
True ELI5 content: https://youtu.be/ws3kWuMi0Y8
tl;dw
1) You orbit a star? ✅ your star is called the sun
2) You have enough gravity to make you round? ✅
but you’re missing one:
3) Do you clear your surroundings? ❌ dwarf planets don’t clear their neighborhood. They don’t clear their orbit of other objects.
One major industry on Pluto is mining for plutonium to power cities. Due to excessive drilling by Plutonian corporations, Pluto shrunk and led Earth’s astronomers to reclassify it as a dwarf planet rather than a planet. This decision angered the local population and is actively fought against by the Plutonian elite.
It is now seen as no different to the dozens of similarly-sized bodies with irregular, odd orbits. It is now classified instead as a “dwarf planet” the same as all those others. So we now have 8 planets and dozens of dwarf planets
This was a necessary reclassification because we keep finding more and more dwarf planets like Sedna and it had become clear that Pluto is just one of those.
It is far easier to learn 8 planets names and some of the dwarf planets names than trying to learn many dozens of names if we instead called them ALL planets.
Pluto was classified as a planet for many years. The issue was that additional bodies similar to Pluto were then discovered beyond Pluto. At some point the astronomical community felt they either had to choose between adding those other bodies into the solar system, or to delist Pluto from its planet status. They chose the latter. The things like distance, size and characteristic of its orbit are some of the main reasons to call it something other than a bonafide planet.
Ultimately, Pluto doesn’t care.
The planetary society came up with a set of rules for What Is A Planet and they say Pluto is too small with an erratic orbit so it is considered a Dwarf Planet.
A lot of comments on “we discovered other stuff” but not much on why we de-planeted Pluto vs. making the other’s planets.
We updated the definition of a planet with our increased knowledge of space. Key for this are the following
1) Planets are big enough to clear their orbits of other space-stuff. In other words, they have enough gravity to pull the stuff in their orbit into themselves, absorbing them, or their gravity “throws stuff away” out into space. Pluto has enough ‘space junk’ in it’s orbit, it’s clearly not doing this.
2) Planets have strong enough gravity to pull their shape into something close to a sphere. Smaller objects don’t have enough gravity and they have ugly shapes, like potatoes or awkward shapes like that. Pluto and it’s “not quite planet” siblings are not roughly spherical, they are ugly shapes.
Because Pluto is smaller than Earth’s Moon.
It is a Kuiper belt object now. Along with quite a few other bodies. Likely, there will be more as time passes and we see more. Now, oddly enough, Ganymede and Titan are much bigger than earths moon and even bigger than Mercury, but they are not classified as planets because they orbit other planets.
It’s confusing up there!
Latest Answers